Exposition environnementale aux métaux en Nouvelle-Calédonie : déterminants, incidence des cancers et évaluation du risque sanitaire: Rapport Scientifique METALICA-Santé

Résumé fourni par la source

The soils of New Caledonia are rich in metals such as Ni, Cr, Mn, and Co, which can contaminate water, air, soil, or food. Because of their toxicity, metallic elements present in the environment can lead to health effects in humans, but the link with pathologies is difficult to establish. The METALICA-Santé project aims to partially address this question through three main objectives: identifying the environmental determinants of human contamination by metals in New Caledonia; studying cancer incidence as a function of municipal-level exposure scores within an ecological study; and assessing the health risk based on Ni and Cr body burden values in children in New Caledonia. To address these objectives, we relied on urinary concentration results for Nickel, Chromium, Cobalt, and Manganese obtained in the METEXPO study among 732 subjects distributed across New Caledonia.The study of environmental determinants of metal contamination was based on the development of a Geographic Information System, which showed that the level of Ni and Co body burden increases with the proportion of peridotite in the soil around the place of residence and, independently, with the density of air masses originating from mining sites during the preceding period. However, we were unable to demonstrate a link with drinking water contamination, possibly due to missing or incomplete data on water catchments and watersheds. The sparse data on food contamination by metals in New Caledonia were insufficient and did not allow us to explore this potentially important source of contamination.The study of cancer incidence by municipality was based on data from the New Caledonia cancer registry between 2008 and 2018 and on the development of a municipal exposure score derived from METEXPO data. In this study, we observed that the incidence of lung cancer calculated by municipality increased with exposure scores for Ni, Cr, and Mn, but that adjustment for potential confounding factors such as the percentage of smokers made this association disappear. We also observed that the incidence of thyroid cancer increased with exposure scores for Ni, Cr, and Co, even after adjustment. These results, based on an ecological approach (data aggregated at the municipal level), do not allow us to conclude that there is a causal association, but suggest the need to pursue studies conducted at the individual level.The third objective allowed us to conclude that the health risk in children related to Ni ingestion is low, but that it is important to monitor eczema in sensitized individuals. The health risk related to Cr is also low, but requires monitoring because of the proximity of the observed body burden to toxicological reference values. It also seems useful to assess in the future the risk associated with inhalation of dust from mining areas.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.